I do not suppose this has ever been noticed or discussed anywhere before. There are a great many ICAO codes in Eurasia, and particularly in Russia and China, where the last three letters are the same. Some other such airports are scattered around the world. Here goes (what I know), in alphabetical order:

DBBB: Cotonou, Benin

DXXX: Lomé, Togo

HSSS: Khartoum, Sudan

NVVV: Port-Vila, Vanuatu

NWWW: Nouméa, New Caledonia

OIII: Tehran (Mehrabad), Iran

TFFF: Fort-de-France, Guadeloupe

UAAA: Almaty, Kazakhstan

UBBB: Baku, Azerbaijan

UEEE: Yakutsk, Russia

UHHH: Khabarovsk, Russia

UIII: Irkutsk, Russia

UKKK: Kiev (Zhuliany), Ukraine

UOOO: Norilsk, Russia

URRR: Rostov-on-Don, Russia (CLOSED and replaced by URRP)

USSS: Ekaterinburg, Russia

UTTT: Tashkent, Uzbekistan

UWWW: Samara, Russia

VCCC: Ratmalana, Sri Lanka

VHHH: Hong Kong, China (SAR)

VYYY: Yangon, Myanmar

WAAA: Makassar, Indonesia

WIII: Jakarta (Soekarno-Hatta), Indonesia

WSSS: Singapore, Singapore

ZGGG: Guangzhou, China

ZHHH: Wuhan, China

ZLLL: Lanzhou, China

ZPPP: Kunming, China

ZSSS: Shanghai (Hongqiao), China

ZUUU: Chengdu, China

ZWWW: Ürümqi, China

Special mention to CYYY (Mont-Joli, Canada) and, the king of them all, MMMM (Morelia, Mexico).

A few codes miss by a hair's breadth: for instance GMMN (I have never been able to understand where the 'N' in its IATA code comes from. This is of special importance as this country's flag carrier is joining Oneworld). Furthermore, when Hong Kong is VHHH, Macau could just as well have been VMMM. Why VMMC?

All in all, a very intriguing list. Thoughts?

In grieving remembrance of the thousands of people who lost their lives on ET-AVJ, PK-LQP, XA-UHZ, S2-AGU, CP-2933, SU-GCC, EI-ETJ, D-AIPX, PK-AXC, 9M-MRD, VT-AXV and above all 9M-MRO, besides many more. Your deaths are not in vain. Safety first, always.

Furthermore, when Hong Kong is VHHH, Macau could just as well have been VMMM. Why VMMC?

All in all, a very intriguing list. Thoughts?

Nice list! I'm surprised that pattern is so common given how awkward they'd be over the radio; it's easier to catch a series of differing phonetic letters instead of trying to count three WHISKY in a row.

I always remembered VHHH as Hong Kong Harbour but I doubt that had any official basis.

While all major airports in Germany start with EDD, there isn't an EDDD airport. They could have used it for Dusseldorf, but that became EDDL. Dresden became EDDC.

Some other countries also follow this system of fixing the middle two letters, like neighbouring Austria, which has LOW*, and Malaysia, which has WMK* (Peninsular), WBK* (Sabah) and WBG* (Sarawak). The big exception is WMSA (Subang Airport).

N.B. Rephrasing my question more clearly: where does the N in CMN (ICAO code: GMMN) come from? This is a simple explanation of my cryptic question in the first post. (It is certain that Royal Air Maroc is joining Oneworld, and announcing it on Wednesday.)

In grieving remembrance of the thousands of people who lost their lives on ET-AVJ, PK-LQP, XA-UHZ, S2-AGU, CP-2933, SU-GCC, EI-ETJ, D-AIPX, PK-AXC, 9M-MRD, VT-AXV and above all 9M-MRO, besides many more. Your deaths are not in vain. Safety first, always.

East Texas Regional Airport (Longview, TX), gets its code from the fact that it's in Gregg County: KGGG. Served by AA. That's the only "triple code" assigned to a US airport with commercial service, although there are a couple of GA and military airfields that have triples.

While Changi uses WSSS, Seletar Airport (which was meant to start ops in early Dec but hasn't done so due to Malaysian belligerence), is WSSL. Paya Lebar Air Base, which is usually used by VVIPs (e.g. heads of state), is a military base, and has had some very rare SQ diversions, is WSAP.

According to Wikipedia, Casablanca Airport was once Nouasseur Air Base, and even today locals call it "Nouaceur" which is the name of the province it is located.May be that's the reason of the "N" in the ICAO code.

What about those ICAO LOCIDs I have in my logbook, ETAR, ETAF, ETMN, ETNN and ETAD, all in Germany.

GF

Looks like they're all military. In Germany civilian airports start with ED and military airports with ET.

To be precise, before the fall of the Wall, ED airports were West German and ET were East German. After reunification ED got civil airports and ET, military airports.-----------------------------------------------------------------------------------------------------------------------------------------------------

SRQKEF wrote:

There are also some airport codes that start with the same three letters, such as Mexico City (MMMX) .

While Changi uses WSSS, Seletar Airport (which was meant to start ops in early Dec but hasn't done so due to Malaysian belligerence), is WSSL. Paya Lebar Air Base, which is usually used by VVIPs (e.g. heads of state), is a military base, and has had some very rare SQ diversions, is WSAP.

Yes. XSL (Seletar) was supposed to have service to SZB, but I don't know what happened. Changi uses WSSS and the smaller Seletar uses WSSL; in contrast, Colombo (Bandaranaike) uses VCBI, while the smaller Ratmalana uses VCCC.-----------------------------------------------------------------------------------------------------------------------------------------------------

danvs wrote:

According to Wikipedia, Casablanca Airport was once Nouasseur Air Base, and even today locals call it "Nouaceur" which is the name of the province it is located.May be that's the reason of the "N" in the ICAO code.

Thank you very much for the help. The 'MN' appears in not only the ICAO code (GMMN) but also the IATA code (CMN).-----------------------------------------------------------------------------------------------------------------------------------------------------

Eindhoven wrote:

And there are repeating codes where the first two are the same as the last two, such as EHEH for EIN.

In grieving remembrance of the thousands of people who lost their lives on ET-AVJ, PK-LQP, XA-UHZ, S2-AGU, CP-2933, SU-GCC, EI-ETJ, D-AIPX, PK-AXC, 9M-MRD, VT-AXV and above all 9M-MRO, besides many more. Your deaths are not in vain. Safety first, always.